Looking forward to this new project of mine and I’m no mechanic but wanting to learn as I go..I have a 1992 dodge 250 diesel manual 4x4..because I have a manual, wanted to ask if it matters if I replace the rear differential with an automatic rear differential? Or will it mess with the 4x4? (FYI..the rear differential gears cracked in my truck so I figured to just replace the whole thing instead of having to mess with replacing the gears which looks complicated) Any tips?

 

I am no gear expert, but I don't believe that there is a difference as pertaining to the transmission. There is a difference in the gear ratio, 3.54 v.s. 4.10 for example and this makes quite a difference. The experts should chime in, welcome to the board...Mark

 

Thanks for the welcoming..so I’ll have to check what the ratio is cuz I don’t know what that is..do you know if there is anywhere on the truck that says what the ratio is? Appreciate ya getting back to me

 

As long as you use a rear axle with the same gear ratio it can be out of a manual or an auto Cummins truck.
The W250 gassers of that era would have a smaller Dana 60 rear axle and should be avoided.

Depending on where you are located I would have a few rear axles here at my shop if you are in the north east of the USA.

 

I think the ratio is stamped on the cover? Or on a tag on the cover bolt? I get my trucks & rearends mixed up.

Or, jack up the rear. Make a mark on the tire and driveshaft. Count how many revolutions the driveshaft turns to one rotation of the tire. That's your ratio.

And welcome to the forum.

 

There is a tag under the bolt on the cover front and back that list the gearing.
There is also a sticker under the hood that lists factory options, including the gearing. Neither of these might be legible at this point due to age.

You can jack up the rear and count tire to driveshaft revolutions or pull a cover and look for numbers stamped into the ring gear.

Any or all of these will help with getting the gearing of that truck.

 

I don't know why most of my post is crossed out...but the info is in there if you need it......

 

Best sure fire way is to pull the cover and check the stamping on the ring gear, it will say somewhere what the ratio is.

Wondered why it was all crossed out like that....too funny.

 

I would look for a 89-91 rear end... these have stronger 35 spline shafts. OTOH, its the 91.5-93 trucks with 32 splines that seem to more commonly have the powr-lok traction aid.
I put a 2ndgen Dana 80 in one of my trucks, and a gas D60 in another (w/ $52 amazon alloy shafts) Both holding up fine.

Bottom line - there's lots of options.

 

Ollie, you didn't pay your dues yet this year, did you?

 

It wasn't me, but someone seems to be saying the correct answer is the first one, just a theory...Mark